major chronic inshore marine pollution problems can often be attributed to the local discharge of large volumes of wastes. these include materials which are partially biodegradable, such as raw sewage, sewage sludge, food and beverage processing wastes, pulp and paper mill effluents, woolen and cotton mill wastes, and sugar refinery effluents. untreated sewage is a direct health threat on some beaches, especially during recreational seasons. discharge on or near shellfish beds presents a greater risk to human health through the consumption of contaminated seafood. nutrient increase is often associated with sewage, and the impact of this has been perceptible in many coastal regions. the effects of nitrogenous wastes are usually most obvious, and phosphate may alter the species composition of phytoplankton populations. the effects of oil pollution on marine systems are probably of a relatively short-term nature (a few years) and apart from some special cases (mangroves, coral reefs), are easily repaired by nature itself. of course, bathing beaches and oysterbeds suffer considerable damage and seabirds are wiped out by the thousands, but the real long-term problem is the continuous build-up of nonbiodegradable elements and compounds in the marine environment